Electronic Supplementary Material

Dual-functional aluminum(III)–based Electrochemiluminescent detection of gene mutation

Yan Hao, Bin Zhou, Yanjuan Tang, Peihui Yang*

Department of Chemistry, Jinan University, Guangzhou 510632, P. R. China

Corresponding author: Peihui Yang, E-mail: , Tel/ Fax: +86-20-85223039

Experimental section

Preparation of CdS QDsand Nafion-PANI

L-cysteine-capped CdS QDs was synthesized according to a published procedure [33].In a word, CdCl2·2.5 H2O (0.158 g dissolved in 30 mL of ultrapure water) stirred with L-cysteine solution (0.242 g dissolved in 10 mL of ultrapure water) at 25 °C. The mixture was injected into Na2S·9H2O solution (0.508 g in 30 mL of ultrapure water), and then, an orange–yellow solution obtained. Subsequently, the prepared solution continuously refluxed for 6 h, and then, centrifugedand thoroughly washed the resultant precipitates with ethanol twice and ultrapure water five times. At last, redispersing the obtained precipitate into ultrapure water, and collecting the freshly prepared solution of CdSQDs.

Nafion-PANI film was synthesized according to a published reference [34]. 0.298 g of aniline and 0.186 g ((NH4)2S2O8were dissolved in 10 mLHCl (1.0 M) aqueous solution, respectively.The prepared ((NH4)2S2O8 solution added into the prepared aniline solutionquickly, which the initial ratio of ((NH4)2S2O8 to aniline was 1:4. The polymerizationreaction conducted for 10 min under stationary state. And then, filtering the obtainedpolyaniline precipitate, and washingthe precipitate with ultrapure water for five times.Finally,the purified polyaniline precipitate dried under vacuum condition at 45°C for 24h.20mg prepared polyaniline dispersed in 40 mLof ultrapure water to obtain a 0.5g·L-1suspension under sonicated conditions. 40 mL preparedpolyaniline (0.5g·L-1) added to 10 mLNafion solution (0.5%) under sonicated conditions for 5 min at room temperature and thenstored for the next stage of experiments.

Results and discussion

Detection of target ssDNA

AFM images shows thatthe ssDNA-functional analysis interface is relatively smooth (Fig. S1a). After incubated with targetssDNA, the analysis interfacepresents some littleknaps (Fig. S1b). These results clearly demonstrated the identification capability of the ECL analysis platform for targetssDNA.

Fig. S1AFM images of (a)ssDNA-functional analysis interfaceand (b)the analysis interface incubated with targetssDNA

Optimization of experimental conditions

Tooptimizedetection performance of the sensing platform,several important parameters were studied.Fig. S2a and S2b in theElectronic Supporting Materialexhibits the effect of Nafion and PANI on ECL intensity, the best concentration of PANIwas0.2mg·mL-1 and the best volume ratio of PANI to Nafion was3:1. Fig.S2c shows the maximum ECL response when the volume ratio of CdSQDs was 20 μL. The optimal concentration and incubation time ofAl(III)were 4 mM and 15min, respectively (Fig.S2dand S2e).The concentration and incubation time ofssDNA and recognition time of target ssDNA were further optimized to be 3 µM, 40 min, 60min, respectively (Fig.S2f, S2gand S2h).

Fig. S2 ECL intensity of (a) the concentration of PNAI-NF;(b)the volume ratio of Nafion and PANI-NF;(c)the dosages of CdS QDs;(d) the concentrationof Al(III);(e) the incubation time of Al(III); (f) the concentration of ssDNA; (g) the incubation time of ssDNA; (h) the recognition time of target ssDNA,three measurements for each point.

Specificity, reproducibility, and stability of the ECL analysis platform

To estimate specificity,reproducibility, and stability, the ECL analysis platform was investigated. Human serum, bovine serum protein(BSA),and hemoglobin(Hb) as endogenous sample components were used to study the specificity of the ECL analysis platform. Fig.S3a shows that the endogenous sample components have no significant effect on the standard solution of complementary target ssDNA, indicatinga satisfactory specificity of the ECLanalysis platform. In addition, five analysis interfaces were prepared at one time to detect target ssDNA for illustrating the reproducibilityof the ECL analysis platform.RSD was 4.85% for the ECL response, which indicated that theanalysis platform possessed good reproducibility.The stability of the ECLanalysis platform wasexamined by consecutive cyclic potential scans for 16 cycles: RSD = 4.45% (Fig. S3b). Moreover, the ECL intensity was 94.51% of the initial ECL value, after a storage period of 10 days at 4 °C. The results showed that the ECLanalysis platform had satisfactory specificity, reproducibility and stability.

Fig. S3 (a)Specificity of the analysis platform after incubation with different endogenous sample components; (b)The ECL signal of the assay in PBS (0.1 M, pH7.4), containing 0.1 mol·L-1 K2S2O8 under consecutive cyclic potential scans for 16 cycles. Scan rate was 100 mV·s-1; scan range from 0 to–1.6 V.

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